ruli

The base finally arrives. Ruliĝi has been on this site for a thousand ranks, doing the intransitive job: a ball ruliĝas down a hill, all by itself. -Iĝ- marks something happening to the subject, so ruliĝi presupposes a ruli for it to be built from, and that is the word on this page. Ruli is transitive and needs an object: you roll something. Turni and turniĝi split the same way, and the igi and iĝi article sets out the pattern in full. In practice this pair is the cleanest illustration of it in the language, because rolling is a thing that both happens and is done.

A note on rulseĝo. A wheelchair is rulseĝo: rul- plus seĝo, a rolling chair. This is worth pausing on because the compound could have gone several ways and the language chose the honest one. Not radseĝo from rado, which would name the hardware; not invalidseĝo, which would name the occupant. Rulseĝo names what the thing does. Esperanto compounds are read right to left for what the word is and left to right for what qualifies it, so this is a chair, and rolling is how it works.

The rest of the family, all regular. Rulo is a roll or a scroll, rulaĵo a rolled-up thing, rulado the rolling, rulebla capable of being rolled, forruli to roll away, enruli to roll in, and rulkurteno is a roller blind. None of them needs looking up once you have the root and the affixes.